#include "bits/stdc++.h"
using namespace std;

typedef long long Int;
#define REP(i,n) for(int (i)=0;(i)<(int)(n);++(i))

int a[100];
int dp[10000];

bool solve(int N) {
	int S = 0;
	REP(i, N) S += a[i];
	if (S % 2 == 1) return false;
	dp[0] = 1;
	REP(i, N) for (int w = S / 2; w >= 0; w--) {
		if (dp[w])
			dp[w + a[i]] = 1;
	}
	return dp[S / 2];
}

int main() {
	int N; cin >> N;
	REP(i, N) cin >> a[i];

	cout << (solve(N) ? "possible" : "impossible") << endl;

}